Nitrox question

[Stryker]

Anyone who has ever had pure oxygen (in the hospital or somewhere else) knows that it definitely makes you feel "giddy"... now whether or not that is considered "narcotic" or not is up to the medical field.... course as little as is known about the narcotic effects of nitrogen, there is even less medical evidence on Oxygen....

 

[Sideband]

just ask the LDS if they have "oxygen compatible air".

Lol. I know exactly what you mean but I wonder what that looks like to someone new.

Yeah...sure. After I ask if their 'air is compatible with Oxygen' I'll make sure to ask them to 'rotate my hoses' and get my 'fins re-soled'.

Joe

 

[Otter]

Actually I have done plenty of searches and plenty of reading on the subject and since Otter spoke with such conviction on the topic I thought maybe he had found some proof to finally put this issue to rest. I certainly have not found anything concrete to say with such certainty that oxygen contributes to narcosis.

Since apparently we both have read various documents on O2 narcosis, I am not sure what you are asking for in terms of proof, but here is a link that most explicity talks about O2 narcosis and is not written by someone in the diving industry.

 

[OE2X]

I don't know if this was for my benefit but it was unneccessary (but still appreciated). It does however provide the basis for my question to OE2X...if you limit yourself to 100fsw on air why are you willing to go deeper with 32%?

Personally I will very occasionally push 32% to a max depth of 130' . . If I know that I'm going to spend a greater amount of time at 130' I will use 30% so as not to approach 1.6 . There is an agency that has subsribes to a standard of only using 32% to 100' and above. Deeper than that you should use trimix. Not being trimix certified - at this point that is not an option.

To answer your question a bit differently: The reason I prefer to dive 32% deeper than 21% is because at all recreational depths my bottom time is significantly longer and with a much lower EAD. It lowers your nitrogen loading which will lessen the risk of DCS as long as you adhere to the profiles.

 

[recdiver]

Personally I will very occasionally push 32% to a max depth of 130' . I will only allow myself to be there for a short period of time so that I'm still under 1.6. To achieve 1.6 you have to have your bottom time at 18 minutes. Considering your EAD is 107' this gives you a larger saftey margin. If I know that I'm going to spend a greater amount of time at 130' I will use 30% so as not to approach 1.6 . There is an agency that has subsribes to a standard of only using 32% to 100' and above. Deeper than that you should use trimix. Not being trimix certified - at this point that is not an option.

To answer your question a bit differently: The reason I prefer to dive 32% deeper than 21% is because at all recreational depths my bottom time is significantly longer and with a much lower EAD. It lowers your nitrogen loading which will lessen the risk of DCS as long as you adhere to the profiles.

I understand the reasons for using Nitrox over air in general (longer bottom time and less nitrogen). I just don't see the connection with being ok with air up to 100fsw but only using Nitrox below that. It seems to me there are more reasons to use Nitrox up to 100fsw and air after that (if not trained for trimix).

 

[StSomewhere]

here is a link that most explicity talks about O2 narcosis and is not written by someone in the diving industry.

1978?

 

[padiscubapro]

Why? Because O2 is considered as narcotic (some theories suggest even more so) as Nitrogen.

.

bULLs**t What evidence thereis is that Oxygen IS LESS NARCOTIC than Nitrogen at exposures NORMALLY seen by divers. The therory most are using is for INERT GASES!!(your link later on at least states the mechanism is different than other gases).. Oxygen is not inert, its used heavily by the body and there is little increase at the cellular level (the narrcotic theory is based on lipid solubility)..

Most are willinng to accept at high exposure level it is probably somewhat narcotic (not enough study has been done) but at those exposures you would be convulsing (working hard), (or dead - very high exposures) anyway.. The study you quted is the lowest exposure I have seen but ts still above the normal exposure levels.. I'dlike to see how they quantified a 10% reduction in mental ability.. Also the study does nothing to see what various oxyegn fractions (other than strictly po2).. its still to narrow a test to say that oxygen is narcotic.

If you followed the therory (but improper use since its an INERT gas theory)oxygen would be at least twice as narcotic as nitrogen that means anyone doing a hyperbaric treatment (normally 2.8 atas) on 100% oxygen would be blasted, this simply is not the case.. The people are clear headed, if there is a reduction its imperceptable (I amwilling to acceptthe fact that the one study see might have measured some small change)..

I HAVE played games with different mixes, and I know on my body I can see a difference with even a few percent.. I couple of years back I did some test on a 150ft dive, I had 26% in one tank and Air in another (as sling bottles), by buddy would randomly give me a tank and I would have to ID it air or 26%, I was able to ID thes tank 100% of the time, it was really easy when the "switch" was an atual mix switch..

If a real detailed study is ever done it will probably show that in the range commonly used by divers there is a reduction of overally narcosis due to reducing the stronger inert gases (one gas being less narcotic than the other) and that at higher exposures it will have some narcopotency..

Even Helium which people say is not narcotic starts to act narcotic at high exposures as documented and tagught by COMEX to saturation divers..

I actually decended on 26% that I had on my back tanks.. I was unsure how the tests were going to run.. The first tank my buddy gave me was air and I knew it immediately..

 

[OE2X]

I understand the reasons for using Nitrox over air in general (longer bottom time and less nitrogen). I just don't see the connection with being ok with air up to 100fsw but only using Nitrox below that. It seems to me there are more reasons to use Nitrox up to 100fsw and air after that (if not trained for trimix).

What is the deepest you will go on air? Why?

You are going to do two dives with a one hour SI. One tank has 32% and one has air. Your plan is to do do the deep dive as your first dive - staying within rec limits. Which gas will you choose? Why?

Yesterday as an example I dove with a buddy who was using air. We dove to 110' and had around 21 minutes of bottom time. He had 5 minutes of deco obligation while I still had about 9 minutes of NDL. If something had happened and one of us had to surface, which person would you have wanted to be?

FWIW - I now dive almost exclusively on 30 -32%.

 

[Wijbrandus]

OE2X, I think you hit the nail on the head. If nitrox is available, you are certified to use it, and you are diving within recreational limits, I don't know of any reason NOT to use it.

Is there a reason to dive air instead of nitrox?

 

[jonnythan]

OE2X, I think you hit the nail on the head. If nitrox is available, you are certified to use it, and you are diving within recreational limits, I don't know of any reason NOT to use it.

Is there a reason to dive air instead of nitrox?

$15 vs $4 to fill an Al 80 with the stuff.

Sometimes it's worth it, sometimes it's not.